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Selective avoidance of lymphatic irradiation in the conservative management of breast cancer.

High-dose lymphatic irradiation is a contributory factor to the morbidity of treatment after local excision and high-dose radiotherapy for early stage breast cancer and may detract significantly from the cosmetic result. The apparent inability of lymphatic irradiation to influence the survival of patients with early stage breast cancer supports an argument for the selective avoidance of regional radiotherapy in a proportion of patients. Based on a review of the effects of lymphatic radiotherapy on lymphatic control, complications, cosmesis, survival and the effects of withholding lymphatic irradiation, recommendations are made for the selective treatment of patients at high risk of regional recurrence. In patients submitted to full axillary dissection, node negative patients require no lymphatic irradiation. After full axillary dissection radiotherapy is confined to the supraclavicular fossa in patients with heavy axillary involvement. A policy for patients having limited axillary dissection is discussed which identifies approximately 50% of patients as eligible for careful watch policy following local excision and high-dose radiotherapy to the primary disease.

Breast Neoplasms↗

Central lymphatic irradiation for stage III nodular malignant lymphoma: long-term results.

PURPOSE: To report the long-term results of central lymphatic irradiation for stage III nodular malignant lymphoma. PATIENTS AND METHODS: Between 1969 and 1985, 34 patients (26 with nodular poorly differentiated lymphoma, four with nodular mixed lymphocytic/histiocytic lymphoma, and four with nodular histiocytic lymphoma) were treated with central lymphatic irradiation. Median age of the group was 51 years (range, 30 to 73). There were 15 men and 19 women. Staging work-up included a physical examination and bone marrow biopsy in all patients. Seventy-four percent had a lymphangiogram (LAG) and 44% a laparotomy (LAP). Eighty-two percent had either a LAP or a LAG. Thirty-two patients were Ann Arbor stage IIIA and two were stage IIIB. All patients received lymphatic irradiation that encompassed cervical, supraclavicular, axillary, mediastinal, paraaortic, mesenteric, pelvic, and femoral lymphatics to total doses ranging from 20 to 30 Gy in 1.0- to 1.8-Gy fractions. Waldeyer's ring was initially treated in 17 patients. Follow-up information is available on all 34 patients. Median follow-up is 9 years, 8 months (range, 15 to 244 months). RESULTS: Life-table actuarial overall, disease-free, and cause-specific survival rates at 15 years are 28%, 40%, and 46%, respectively. Only one relapse was observed after 9 years. Disease-free survival was significantly improved in patients with five or fewer sites of involvement (P = .02). Age, sex, B symptoms, histology, and technique of irradiation were not prognostically significant. Salvage therapy, including further irradiation and/or chemotherapy, was delivered to 20 patients. Ten percent of these patients remain alive without evidence of disease. Toxicity data were available for the patients treated at the Medical College of Wisconsin (MCW). Radiation Therapy Oncology Group (RTOG) acute hematologic, gastrointestinal, and salivary toxicity scores were < or = 2 in 83% of patients. Late toxicity scores were < or = 2 in 96%. Persistent xerostomia was noted in 23% of patients who received initial treatment to Waldeyer's ring. CONCLUSION: These results suggest that initial comprehensive central lymphatic irradiation may be the preferred approach to achieve a durable relapse-free interval for this group of patients.

Adult↗

Hematologic recovery after central lymphatic irradiation for patients with stage I-III follicular lymphoma.

BACKGROUND: The authors previously reported that central lymphatic irradiation (CLI) can induce molecular remission in patients with Stage I-III follicular lymphoma, as measured by polymerase chain reaction analysis for t(14;18) (q32;q21). Hematologic toxicity has been considered a major consequence of CLI. This study was undertaken to analyze the patterns of hematologic recovery after CLI. METHODS: Thirty-three patients with Stage I-III follicular lymphoma were treated with CLI between January 1993 and February 1998. CLI consisted of irradiation to mantle, upper two-thirds of abdomen, and pelvic fields. Each field was treated to 30.0-30.6 grays (Gy) at 1.5-1.8 Gy per fraction, with a boost to 36.0-39.6 Gy at the same rate to the sites of macroscopic disease. A break of approximately 4 weeks was given after treatment of each field. Twenty-four patients who were followed for a minimum of 1 year from the end of CLI form the basis of this analysis. Fourteen patients were male. Three patients had Stage I disease, 6 patients had Stage II disease, and 15 patients had Stage III disease. The International Prognostic Index (IPI) for malignant lymphoma was 0 for 5 patients, 1 for 13 patients, and 2 for 6 patients. The Eastern Cooperative Oncology Group performance status was 0 for 21 patients and 1 for 3 patients. The median values for their pretreatment characteristics were as follows: age, 60 years (range, 34-73 years); height, 173 cm (range, 155-193 cm); weight, 79 kg (range, 57-107 kg); body surface area (BSA), 1.95 m(2) (range, 1.61-2.31 m(2)); bone marrow cellularity, 27%(range, 2-75%), platelet count, 233,000/mm(3) (range, 139,000-339,000/mm(3)), white blood cell (WBC) counts, 6400/mm(3) (range, 4200-10,900/mm(3)); and hemoglobin, 14.5 mg/dL (range, 11.8 -16.6 mg/dL). The median duration of CLI was 159 days (range, 137-345 days). Ten patients had cardiovascular disease. The number of sites receiving a boost dose of > or = 36.0 Gy was 0 sites in 1 patient, 1 site in 6 patients, 2 sites in 11 patients, 3 sites in 5 patients, and 4 sites in 1 patient. The platelet, hemoglobin, and WBC counts were followed every 3 months after completion of CLI. These counts were normalized to the pretreatment counts for statistical analyses. Univariate and multivariate analyses were performed to investigate the correlations between patient factors and hematologic status at 1 year posttreatment. Pearson correlation analysis was used for the continuous factors (patient age, height, weight, BSA, bone marrow cellularity, and duration of CLI), and the Mann-Whitney test was used for categoric factors (IPI, gender, performance status, stage, number of sites receiving > or = 36.0 Gy, and presence or absence of cardiovascular disease). RESULTS: There was continued recovery, essentially approaching the pretreatment levels, over 3 years for platelet, WBC, and hemoglobin counts. Factors that were associated significantly with normalized platelet counts at 1 year by univariate analyses were age (P = 0.015) and cardiovascular disease (P = 0.041). Age was the only significant factor by multivariate analyses, with older patients having lower platelet counts at 1 year posttreatment. No factors were found that were associated significantly with 1-year normalized WBC or hemoglobin levels by either univariate or multivariate analyses. CONCLUSIONS: All three of the hematologic components (platelets, WBC, and hemoglobin) essentially recover after patients undergo CLI over a 3-year period. Older age was the only significant adverse factor that affected the platelet recovery, as detected by multivariate analysis. (c) 2001 American Cancer Society.

Adult↗

Three-dimensional treatment planning for central lymphatic irradiation.

The purpose of this study was to investigate the applicability of 3-dimensional (3D) treatment planning for central lymphatic irradiation (CLI). CLI requires more than 1 course of treatment with large, highly blocked, overlapping beams, and careful planning is required to ensure that such treatments are delivered safely and effectively. Three patients were selected for this study. Each patient completed at least 1 course of radiation therapy for CLI and was scheduled to receive irradiation to an adjacent area with overlapping beams. Two treatment plans were generated for each patient: a standard, 2-dimensional (2D) treatment plan and a 3D treatment plan designed to mimic the standard plan, taking advantage of unique 3D features. The time required to complete the treatment plans and differences in the treatment planning processes were noted. The time required to generate a 3D treatment plan was approximately the same as the time required to generate a standard 2D treatment plan; however, the 3D planning process required less redundancy of data entry than the 2D process. The 3D treatment plan was qualitatively similar to the standard 2D treatment plan; however, differences in beam penumbra and beam junctions were noted, and are most likely due to differences in the dose-calculation models used in these 2 treatment planning systems. Dose-volume histograms (DVHs) were calculated for the spinal cord and were found to be useful to the physicians for quickly and accurately evaluating the presence or absence of hot spots in the junction region. 3D treatment-planning has some advantages over 2D treatment planning for CLI; the main advantage of the 3D treatment plan is that it provides a single plan for each patient with multiple views of the data, including different planar cross-sections and DVHs. For the 2D system, a separate plan was generated for each view, requiring redundant data entry. The quality of the output of the 3D treatment plans is superior to that of 2D treatment plans, but the clinical utility is about the same. Currently, the time required for 2D and 3D treatment plans is similar. However, as dosimetrists become more familiar with 3D treatment planning systems, we expect this familiarity and regularity of use to translate into a significant time advantage.

Humans↗

Central lymphatic irradiation for stage I-III follicular lymphoma: report from a single-institutional prospective study.

PURPOSE: This study was undertaken to update our experience with follicular lymphoma treated with central lymphatic irradiation (CLI). METHODS AND MATERIALS: A total of 47 patients were treated with CLI between January 1993 and March 2000 in a prospective manner. CLI consisted of mantle, whole abdomen, and pelvic radiation fields with a 1-month break after each field. Each field was treated to 3000-3060 cGy at 150-180 cGy per fraction followed by a boost dose of 900 cGy to the areas with gross disease. The median age was 52 years (range: 29-73 years). There were 29 males. The diagnoses were as follows: follicular small cleaved-cell lymphoma, 23 patients; follicular mixed-cell lymphoma, 19 patients; follicular large-cell lymphoma, 5 patients. Ann Arbor stages were as follows: I, 5 patients; II, 14 patients; and III, 28 patients. The International Prognostic Index (IPI) categories were as follows: 0, 14 patients; 1, 24 patients; and 2, 9 patients. M. D. Anderson Tumor Score was as follows: 0, 14 patients; 1, 18 patients; 2, 9 patients; 3, 4 patients; 4, 1 patient; and unknown, 1 patient. Two patients had abnormal LDH levels, and 11 patients had beta2M levels >2 mg/dL. Gender, pathology, stage, IPI, Anderson Tumor Score, beta2M, and number of disease sites were examined for significance in freedom from progression (FFP) by univariate analyses. RESULTS: The median follow-up was 54 months (range: 8-93 months) for the 45 surviving patients. Every patient achieved a complete response, except for 1 patient whose lymphoma progressed to diffuse large-cell lymphoma during treatment. The 5-year overall survival and FFP were 94% and 53%, respectively. No failure has yet been observed beyond 55 months of follow-up with 13 patients at risk. Patterns of failure were as follows: within the radiation field, 10; outside the fields, 4; and both, 2. Of the seven variables investigated, beta2M >2 mg/dL and IPI >1 were the only significant adverse prognostic factors for FFP (p = 0.023 and 0.046, respectively). CONCLUSIONS: CLI is well tolerated and seems to achieve durable FFP in about half of the patients with Stage I-III follicular lymphoma. Most of the experiences with CLI come from the treatment of Stage III disease and are very similar to our previous experience with combined modality treatment. Whether a plateau in FFP can be maintained beyond 5 years remains to be seen.

Adult↗

Comprehensive lymphatic irradiation for stage II-III non-Hodgkin's lymphoma.

Thirteen patients with stage II-III non-Hodgkin's lymphoma (NHL) and one patient with minimal marrow involvement were selected for treatment between 1964 and 1986 with moderate-dose comprehensive lymphatic irradiation (CLI). This approach has been well tolerated and has produced relapse-free and overall survival rates at 10 years of 60 and 66%, respectively. Salvage therapy for failure following CLI has been possible. CLI produces results comparable to any achieved with combined modality therapy, offers less acute and late toxicity, and requires only 3-4 months for completion.

Actuarial Analysis↗

Central lymphatic irradiation to low dose for advanced nodular lymphoreticular tumors (non-Hodgkin's lymphoma).

Total central lymphatic irradiation (2500-3000 rads in 3 to 6 weeks) including the entire abdomen, the supradiaphragmatic nodal areas, and Waldeyer's ring is being investigated as a potentially curative approach to patients with Stage III disease. Twenty-two patients have been treated (24-month minimum observation). All evidence of disease has disappeared in every patient. Three patients have developed local recurrence; 2 of them received 2000 rads or less. Three patients had marginal recurrences, and 5 developed generalized disease involving viscera. Fourteen patients (64%) are alive and free of any evidence of disease from 24-90 months (median, 54 months). Absolute survival is 82% (18/22).

Adult↗

Serial determination of the bcl-2 gene in the bone marrow and peripheral blood after central lymphatic irradiation for stages I-III follicular lymphoma: a preliminary report.

Two-thirds of patients with follicular lymphoma have rearrangement of bcl-2 major breakpoint region (MBR) through t(14;18) (q32;q21). This rearrangement can serve as a sensitive marker for follicular lymphoma cells. This study was undertaken to assess the molecular complete response rate of stages I-III follicular lymphoma to central lymphatic irradiation (CLI) by detection of PCR-amplifiable bcl-2 MBR rearrangement in the bone marrow and peripheral blood before and after CLI. Twenty patients with stages I-III follicular lymphoma were treated with CLI. Twelve of them were part of a prospective randomization trial comparing CLI with multi-agent chemotherapy. Bone marrow and peripheral blood samples were obtained from the patients before the initiation of treatment. By using the PCR technique, the DNA sequences from the bone marrow and peripheral blood samples that flank the bcl-2 MBR involved in t(14;18) (q32;q21) were amplified. In PCR-positive patients, bone marrow and blood samples were followed at regular intervals during and after CLI. The results of the PCR amplification were correlated with clinical findings. All 20 patients achieved clinical complete response after CLI. Median follow-up was 22 months (range, 12-37 months), and no patient has relapsed. Pretreatment PCR results were available in all patients (19 patients for peripheral blood samples and 16 patients for bone marrow samples). Nine of 19 peripheral blood samples and 9 of 16 bone marrow samples were PCR-positive for bcl-2 MBR rearrangement. Eight PCR-positive patients converted to negative (8 of 9 blood samples and 2 of 3 bone marrow samples) 2-20 months from the first day of CLI. Bone marrow and peripheral blood with PCR-amplifiable bcl-2 MBR rearrangement can be converted from positive to negative after chemotherapy in patients with follicular lymphoma. Early results from our study show for the first time that peripheral blood and bone marrow can be converted from positive to negative after CLI. The prognostic significance of the observed conversions requires longer follow-up.

Adult↗

The significance of molecular response of follicular lymphoma to central lymphatic irradiation as measured by polymerase chain reaction for t(14;18)(q32;q21).

BACKGROUND: More than 80% of the patients with follicular lymphoma have a characteristic chromosomal translocation, t(14;18)(q32;q21), at the major breakpoint region (MBR) or minor cluster region (MCR) involving the bcl-2 oncogene. This study was undertaken to assess the significance of the molecular response rate measured by the polymerase chain reaction (PCR) evidence of translocation among patients with Stage I to III follicular lymphoma treated with central lymphatic irradiation (CLI). METHODS AND MATERIALS: Thirty-three patients with Stage I-III follicular lymphoma were treated with CLI on a prospective protocol. Bone marrow and peripheral blood samples were obtained before CLI for PCR analysis of t(14;18)(q32; q21). PCR-positive patients were followed by PCR analysis at regular intervals during and after CLI, and the results were correlated with clinical outcome. The following pretreatment factors were also investigated for their relationship to relapse and molecular response: gender, age, lactate dehydrogenase (LDH) and beta-2 microglobulin (beta2M) levels, Ann Arbor stage, and International Prognostic Index (IPI) for malignant lymphoma. RESULTS: The subjects were 19 men and 14 women, with a median age of 52 years (range 30-69), who started CLI between January 1993 and February 1998. Median follow-up was 44 months (range 12-67), and all but 2 patients were still alive at the last follow-up. Four patients were Stage IA, 8 were Stage IIA, 19 were Stage IIIA, and 2 were Stage IIIB. Two patients had abnormal LDH levels (> 618 U/dL) and 7 patients had abnormal beta2M levels (> 2 mg/dL). Nine patients had IPI = 0, 16 had IPI = 1, and 8 had IPI = 2. All patients achieved complete response (CR). Twelve patients have relapsed to date. The median overall time to relapse was 54 months. The actuarial proportion of patients free from relapse at 3 years was 87% (95% confidence interval [CI] 69-95%). A total of 287 PCR results were available, 64 from bone marrow and 223 from peripheral blood. Pretreatment PCR data were available for 27 patients, of whom 21 were positive and 3 were unambiguously negative (in blood and bone marrow for both MBR and MCR). For the 19 PCR positive patients for whom we had post-treatment results, there was a clear and steady decreasing trend toward loss of PCR positivity (49% positive for bone marrow and 32% positive for peripheral blood at 3 years). There was a clear trend for increasing PCR positivity with increasing IPI: 10% for IPI = 0, 31% for IPI = 1, and 63% for IPI = 2 at 3 years for blood. The same trend was also observed for bone marrow. The IPI was the only statistically significant predictor for relapse with a relapse-free survival of 91% at 3 years for IPI < 2 and 75% for IPI = 2 (p = 0.024, log-rank test). CONCLUSION: Molecular response to CLI occurs gradually over years. High IPI is a negative predictor for molecular response and relapse-free survival.

Adult↗

Total lymphatic irradiation and bone marrow in human heart transplantation.

Six patients, aged 36 to 59 years, had heart transplants for terminal myocardial disease using total lymphatic irradiation (TLI) and donor bone marrow in addition to conventional therapy. All patients were poor candidates for transplantation because of marked pulmonary hypertension, unacceptable tissue matching, or age. Two patients are living and well more than four years after the transplants. Two patients died of infection at six and seven weeks with normal hearts. One patient, whose preoperative pulmonary hypertension was too great for an orthotopic heart transplant, died at 10 days after such a procedure. The other patient died of chronic rejection seven months postoperatively. Donor-specific tolerance developed in 2 patients. TLI and donor bone marrow can produce specific tolerance to donor antigens and allow easy control of rejection, but infection is still a major problem. We describe a new technique of administering TLI with early reduction of prednisone that may help this problem.

Adult↗

A prospective randomized study to compare the molecular response rates between central lymphatic irradiation and intensive alternating triple chemotherapy in the treatment of stage I-III follicular lymphoma.

PURPOSE: This study was undertaken to compare the molecular response (MR) rates of 2 regimens, central lymphatic irradiation (CLI) and alternating triple therapy (ATT), in the treatment of Stage I-III follicular lymphoma. MR was defined as disappearance of t(14;18) (q32;q21) amplified by polymerase chain reaction (PCR). PATIENTS AND METHODS: Sixty-five patients with Stage I to III follicular lymphoma were randomized. CLI consisted of the mantle, abdomen, and pelvic radiation fields. ATT alternated among CHOD-Bleo, ESHAP, and NOPP for 12 courses. Bone marrow (BM) and peripheral blood (PB) samples were obtained before treatment for PCR analysis. PCR-positive patients were followed by PCR analysis. The random-effects logistic model was fitted to the data from the posttreatment PCRs. The factors included in the model were treatment arm, type of PCR (BM vs. PB), and time to PCR sample procurement from the date of registration. RESULTS: At a median follow-up of 71 months, the 5-year relapse-free survival (RFS) rates were 45% and 54% for CLI and ATT, respectively (p = 0.42). The probability of attaining an MR increased with time after registration (p = 0.007), was lower for BM compared with PB (p = 0.012), and was higher for ATT than for CLI (p = 0.020). CONCLUSION: ATT regimen achieved a higher MR than CLI, although both arms had similar 5-year RFS.

Adult↗

Is comprehensive lymphatic irradiation for low-grade non-Hodgkin's lymphoma curative therapy? Long-term experience at a single institution.

PURPOSE: This study reports 21 patients with Stage I-III low-grade non-Hodgkin's lymphoma who were treated with comprehensive lymphatic irradiation (CLI) at the University of Florida between 1966 and 1992. METHODS AND MATERIALS: Sites clinically involved with disease were treated with 30 Gy, whereas clinically uninvolved sites were treated with 25 Gy. Median follow-up for the group was 14 years (24.5 years for Stage III patients). RESULTS: Overall absolute survival rates at 5, 10, and 15 years were 84%, 68%, and 34%. Cause-specific survival rates at 5, 10, and 15 years were 84%, 68%, and 56%. Freedom-from-relapse rates at 5, 10, and 15 years were 75%, 58%, and 58%, with no relapses noted after 10 years. Bulky disease (>6 cm) was a significant indicator of poor prognosis for cause-specific survival (p = .01). CONCLUSION: These data support findings from other institutions suggesting a role for CLI as potentially curative therapy with acceptable toxicity and a short treatment time for patients with Stages I and II and limited Stage III disease.

Adult↗

Salvage central lymphatic irradiation in follicular lymphomas following failure of chemotherapy: a feasibility study.

PURPOSE: Management of follicular lymphoma after chemotherapy failure has been controversial and has ranged from watchful waiting to high-dose chemotherapy. High-dose chemotherapy with bone marrow reconstitution may produce clinical and molecular complete responses at the risk of serious morbidity and mortality. It has been previously reported that central lymphatic irradiation (CLI) can achieve long-term relapse-free survival in patients with Stage I, II, or III follicular lymphoma. Therefore, we investigated the feasibility of treating patients in whom front-line chemotherapy failed with salvage CLI instead of instituting more intensive chemotherapy. METHODS AND MATERIALS: Salvage CLI with curative intent for patients with follicular lymphoma was started at The University of Texas M. D. Anderson Cancer Center in 1992. Eleven patients whose disease showed poor response to or relapsed after chemotherapy were managed with this approach. The median age of the patients was 61 years. Criteria for exclusion included bone marrow involvement or other evidence of Ann Arbor Stage IV disease at any time during the course of the disease. Overall survival and relapse-free survival were calculated from the first day of CLI. RESULTS: Ten patients were alive at a median follow-up of 25 months (range 9-73 months). The treatment was well tolerated in general. Two patients could not complete CLI: one 75-year-old patient owing to prolonged platelet count depression and deterioration in general medical condition, and a 66-year-old patient because of exacerbation of preexisting pancytopenia and worsening of heart disease. Everyone who completed CLI remains in remission at the time of this report, except for one patient who had a relapse in the right lacrimal gland at 32 months. This patient was treated with local radiation therapy and is free of disease. Eventual recovery of the blood counts was observed for the patients who completed CLI. CONCLUSION: These results demonstrate for the first time that with CLI, it is possible to achieve complete remission of acceptable quality in follicular lymphoma patients who experience a chemotherapy failure. The main toxicity is limited to transient depression in hematological profiles. The treatment is fairly well tolerated and seems to carry little risk compared with high-dose chemotherapy and bone marrow rescue. Salvage CLI may not necessarily compromise future treatment with chemotherapy, including autologous bone marrow or stem cell transplantation, because the patients' blood counts recover.

Aged↗

Immunosuppressive effect of intra-lymphatic irradiation.

The effect of intra-lymphatic administration of Lipiodol-l131 on the number of T and B lymphocytes, and on the in vivo response to common antigens and to DNCB, was investigated in uremic patients in the pre-transplant period. T lymphocytes have been detected by rosette formation with sheep erythrocytes (E) and B lymphocytes by rosette formation with erythrocytes sensitized with antibody and complement (EAC). After irradiation it was observed a lymphopenia due to a statistically significant decrease in the number of both T and B peripheral blood lymphocytes and a depletion of these cells in the irradiated lymph nodes. Their ability to give delayed hypersensitivity response to common antigens in vivo was lost after intralymphatic irradiation. Two patients were able to develop sensitization to DNCB and this reaction was supressed in one of them by irradiation. These effects of intralymphatic irradiation on the immune system favours further study of this method in clinical renal transplantation.

B-Lymphocytes↗

Stage III nodular lymphoreticular tumors (non-Hodgkin's lymphoma): results of central lymphatic irradiation.

Since 1969, 29 previously untreated patients with Stage III nodular malignant lymphoreticular (MLT) have received total central lymphatic (TCL) irradiation. The volume irradiated included the entire abdomen, Waldeyer's ring, and preauricular nodes in addition to the usual regions encompassed by total nodal irradiation. Doses of 2000--3000 rads in three to six weeks were delivered to the nodal regions, liver, and spleen; fraction sizes ranged from 100 to 180 rads. Patients have been followed from one to ten years (median six years). The actuarial survival is 78% at five years, and the disease-free survival is 61%. There is no difference in disease-free survival of the patients with poorly differentiated lymphocytic vs. those with "histiocytic" or mixed cytology. Men and women had disease-free survivals of 82% and 43%, respectively. The long-term follow-up of these patients indicates that prolonged disease-free intervals are common after TCL irradiation, and some patients may be cured.

Abdominal Neoplasms↗

[Effect of fractionation on the immunosuppressive effect of total lymphatic irradiation (TLI)].

The influence of single dose and fractionation on the immunosuppressive effect of a total lymphoid irradiation (TLI) was investigated by experimentation on animals and compared to literature. Lewis rats were irradiated with a constant temporal dose distribution. The weekly dose of 7,0 Gy was fractionated into 1 X 7,0 Gy, 2 X 3,5 Gy and 7 X 1,0 Gy, with rising total doses. The survival time of cutaneous allografts served as parameter for the immunosuppression; the toxicity of the treatment was related to the immunosuppressive effect. Immunosuppression as well as toxicity showed differences depending on fractionation. For both criteria, the fractionation of 2 X 3,5 Gy per week had better results. The validity of the Ellis formula for the immunosuppression induced by total lymphoid irradiation was restricted.

Animals↗